This invention relates to the rapid development and commercial production of new hybrid seeds and plants therefrom, including melons, vegetables, grains, forages, fibre crops, and other monecious species. More particularly, it provides a technique for the rapid development of new hybrids and for the rapid commercial production of hybrid seeds.
The conventional procedures for developing new hybrids are well known and are described in the literature. The Encyclopaedia Britannica, Macropedia, has extensive sections on "Horticulture" and on "Plant Breeding." While the procedures are known and are widely practiced, their limitations are equally well recognized.
The plant breeder seeking to develop new hybrids will cross (hybridize) two parental lines where each of the lines is composed of plants which are as homozygous (purebred) as possible. Homozygosity, however, is achieved slowly; plants must be selfed (inbred) for a number of generations to obtain an essentially pure breed. From eight to twelve generations is not uncommonly required to produce lines which are sufficiently homozygous so that, when crossed with other homozygous lines, they will yield a population of genetically uniform hybrids.
Moreover, only a relatively limited number of purebred lines are available, and this restricts both the possible number of crosses and the genetic diversity of the hybrids that can be made in any given year.
Still another limitation on the development of new hybrids is that the parent plants, being reproduced sexually, may develop undesirable genetic changes from generation to generation.
A further constraint on existing techniques of hybrid plant development is the fact that many plants produce only a limited number of seeds per plant. This is particularly troublesome because inbred parental lines exhibit low vigor, which manifests itself in low seed yields. Thus, even after superior hybrids have been developed, large scale production of hybrid seed for sale may not be possible for the next year or so.
The above conditions are epitomized in the development of canning and juice tomatoes. A fair number of purebred varieties are obtainable, but due to the limitations above, only a few new hybrids appear on the scene each year.
Accordingly, a principal object of the invention is to provide a technique or method for rapidly developing, and then rapidly commercially producing, new hybrids. A further object is to produce such new hybrids from one or both heterozygous parents, and yet have the hybrid plants be satisfactorily uniform phenotypes. Still another object is to produce superior new hybrids of greater genetic diversity, and without limitation on the homozygosity or heterozygosity of the parents. Yet another object is to produce such hybrids in as little as two or three years, as compared to the eight to twelve years now required for the development and production of new hybrids. Further objects will become apparent as the description of the invention proceeds.